Transcript of "Green chemistry"

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Why do we need Green Chemistry
Objective
• Chemistry is undeniably a
very prominent part of our
daily lives.
• Chemical developments also
bring new environmental
problems and harmful
unexpected side effects,
which result in the need for
‘greener’ chemical products.
Results
• A famous example is the
pesticide DDT.
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What it looks for . . . . .
• Green chemistry looks at pollution prevention on the
molecular scale and is an extremely important area of
Chemistry due to the importance of Chemistry in our world
today and the implications it can show on our environment.
• The Green Chemistry program supports the invention of more
environmentally friendly chemical processes which reduce or
even eliminate the generation of hazardous substances.
• This program works very closely with the twelve principles of
Green Chemistry.
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Goals of Green Chemistry
1. To reduce adverse environmental impact, try appropriate and
innovative choice of material & their chemical transformation.
2. To develop processes based on renewable rather than non-renewable
raw materials.
3. To develop processes that are less prone to obnoxious
chemical release, fires & explosion.
4. To minimize by-products in chemical transformation by
redesign of reactions & reaction sequences.
5. To develop products that are less toxic.
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Goals of Green Chemistry
6. To develop products that degrade more rapidly in the
environment than the current products.
7. To reduce the requirements for hazardous persistent solvents
& extractants in chemical processes.
8. To improve energy efficiency by developing low temperature
& low pressure processes using new catalysts.
9. To develop efficient & reliable methods to monitor the
processes for better & improved controls.
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The 12 Principles of Green Chemistry
3. Minimization of hazardous products
Wherever practicable, synthetic methods should be
designed to use and generate substances that possess
little or no toxicity to people or the environment.
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The 12 Principles of Green Chemistry
6. Design for Energy Efficiency
Energy requirements of chemical processes should
be recognised for their environmental and economic
impacts and should be minimised. If possible, synthetic
methods should be conducted at ambient temperature and
pressure.
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The 12 Principles of Green Chemistry
6. Design for Energy Efficiency
Developing the alternatives for energy generation
(photovoltaic, hydrogen, fuel cells, bio based fuels,
etc.) as well as
Continue the path toward energy efficiency with
catalysis and product design at the forefront.
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The 12 Principles of Green Chemistry
7. Use of Renewable Feedstock
“A raw material or feedstock should be renewable rather
than depleting whenever technically and economically
practicable.”
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The 12 Principles of Green Chemistry 20
7. Use of Renewable Feedstock

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The 12 Principles of Green Chemistry
8. Reduce Derivatives
Unnecessary derivatization (use of blocking groups,
protection/de-protection, and temporary modification of
physical/chemical processes) should be minimised or
avoided if possible, because such steps require additional
reagents and can generate waste.
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The 12 Principles of Green Chemistry
10. Designing of degradable products
Chemical products should be designed so that at the
end of their function they break down into innocuous
degradation products and do not persist in the
environment.
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The 12 Principles of Green Chemistry
11. New Analytical Methods
“Analytical methodologies need to be further
developed to allow for real-time, in-process monitoring
and control prior to the formation of hazardous
substances.”
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The 12 Principles of Green Chemistry
12. Safer Chemicals For Accident Prevention
“Analytical Substances and the form of a substance used
in a chemical process should be chosen to minimise the
potential for chemical accidents, including releases,
explosions, and fires.”
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2. Atom Economy
e.g.
1. Rearrangement Reactions:
These reactions involves rearrangement of atoms
that forms molecule. Hence, the atom economy of these
reactions are 100%.
2. Addition Reactions:
These reactions involves addition of two or more
molecules without elimination that forms molecule.
Hence, the atom economy of these reactions are 100%
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